1. Field of the Invention
The present invention concerns an object shape determining method for deciding the shape of an object which moves through a fluid medium, and more specifically relates to an object shape determining method for deciding the shape of an object as a shape which minimizes aerodynamic noise generated by turbulence and other variations in flow when the object moves through the fluid.
2. Description of the Related Art
When deciding the shape of an object for reducing aerodynamic noise generated by turbulence and other variations in flow when the object moves through a fluid medium, it is mainly the case simply to rely on past experience, and an object shape determining method per se has not existed. Hereinafter, aerodynamic noises is also referred to as "noise".
For example, in designing a vehicle body, aerodynamic noise (noise generated by the air flow on the vehicle body) is detected based on a wind tunnel test, and should such aerodynamic noise not attain a desired value, the shape of the object is modified, and the wind tunnel test is repeated until a shape of the object which reduces the aerodynamic noise to a desired value is adopted. With respect to noise from the duct of a jet engine, it is known that noise can be reduced by making the duct chrysanthemum-shaped in cross-section, however, such a shape must still be determined on a trial and error basis.
In many cases, in addition to the techniques discussed above, a sound-insulating material or the like is used to perform additional noise reduction.
However, when determining the shape of an object according to the above-mentioned conventional techniques, because a trial and error decision process is employed, there are problems in terms of time expenditures required for deciding the shape, and in addition as the shape involved becomes more complex, the shape determination process is accompanied by further difficulty.